This is a 3rd party rpm repository which contains current release MythTV rpms. The original focus laid upon software used in natural sciences, especially in the field of high energy physics, e.g. tools for numerical programming or such for scientific publications. But since then this repository has included many non-scientific software titles, like system tools or multimedia packages, resulting in a far more generic repository.
MythTV packages are usually refreshed monthly (fixes) or on-demand if you post a request to the atrpms mailing list ( http://lists.atrpms.net/pipermail/atrpms-users/)
To install use the following command (for yum) eg
yum install mythtv-suite